Understanding the nexus between energy and water: A basis for human survival in South Africa

Figures & data

Figure 1. Map showing South African climate zones, water source areas, areas of high groundwater use and areas of mine water pollution (adapted from Ololade et al., 2017).

Figure 2. Energy–water nexus scenario in South Africa (adapted from Wang, 2009).

Table 1. Current and proposed energy mix with water requirement implications in South Africa.

Energy source (considering technology efficiency)	Water consumption (considering the water consumption during operations only)	Implication for water quantity/quality (taking the quality of the grey water into account)
Conventional wet-cooling power plant	1.35 m^3/MWh (Eskom, 2011b)	High negative impact on water quantity and downstream water quality (Eberhard, 2000; Von Uexkull, 2004 ; McCarthy & Pretorius, 2009)
Coal – using direct dry cooling technologies to generate electricity	0.66 m^3/MWh (Greenpeace, 2011)	Low negative impact on water quantity and downstream water quality. Has high in-plant electricity usage (de Korte, 2010; Wassung, 2010; Eskom, 2013)
Synthetic liquid fuels, coal and gas (methane)	12 m^3/tonne – 4% Vaal River freshwater system (Sasol, 2014)	High negative impact on water quantity and downstream quality
Integrated gasification combined cycle (IGCC) to generate electricity	3.1 m^3/MWh (Madhlopa et al., 2013)	Low negative impact on water quantity and high negative impact on groundwater quality (Makananise, 2013)
Nuclear energy for electricity generation (once through cooling method)	0.000055 m^3/MWh (WWF, 2014)	Uses seawater; very little water loss; no impact on freshwater quality or quantity; potential environmental damage is the hot water that is released back into the sea that can harm the aquatic species living in it; radioactive waste (Sparks & Mwakasonda, 2006; Sparks et al., 2014)
Shale gas	5 .9 m^3/MWh (Wilson & VanBriesen, 2012)	High negative impact on water quantity and groundwater quality (Wilson & VanBriesen, 2012; Kharak et al., 2013)
Solar power – CPV Technologies	0.015–0.5 m^3/MWh (Leitner, 2002; Fthenakis & Kim, 2010)	No impact on downstream water quality; very little impact on water quantity (Sparks et al., 2014)
Solar power – Parabolic Trough	0.296 m^3/MWh (Macknick et al., 2011)	No impact on downstream water quality; no impact on water quantity except during construction stage (Fthenakis & Kim, 2010)
Wind power	0.0038 m^3/MWh (Macknick et al., 2011)	No impact on downstream water quality; no impact on water quantity except during construction stage (Gleick, 1994; Edkins et al., 2010)
Hydro power	17 m^3/MWh – lost during evaporation (Gleick, 1994)	No impact on downstream water quality; low impact on water quantity due to evaporation loss (Mekonnen & Hoekstra, 2012)
Biofuel (ethanol)	416 000 m^3 of water to grow sugarcane per annum (De Fraiture et al., 2008; Stone et al., 2010)	Low impact on downstream water quality; high impact on water quantity (De Fraiture et al., 2008; Stone et al., 2010)

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